(1) Field of the Invention
This invention is drawn to the field of fluid mechanics, and more particularly, to a novel electromagnetic turbulent boundary layer controller.
(2) Description of the Prior Art
At the interface between a moving marine vessel and its medium, turbulence phenomena exhibit themselves, which, for reasons well known to those skilled in the art, often call for some measure of control. By controllably changing the flow or fluid properties of the medium at the interface, the turbulence may be correspondingly controlled. As one example of a heretofore known fluid or flow turbulence control technique, it is known that polymers locally injected along the interface effect a measure of turbulence control. The long molecular polymeric chains are stretched out and they uncoil themselves along the direction of flow and by action of forming a viscosity gradient with the medium, are able to dampingly absorb energy in directions generally perpendicular to the direction of stretching. Another such heretofore known turbulence control technique deploys a negative pressure porous surface that controllably siphons off the medium below the interface turbulence boundary layer, thereby controllably changing the characteristics of the flow, and therewith control the measure 12 of turbulence generated. These techniques pay the penalties of needing to store a reservoir of polymer or other injectant and of needing to provide a reserve of ready power to suction off the medium, which are undesirable in many applications environments.
Furthermore, it is known that by controllably changing the character of the turbulent boundary layer formed around the surface of the vessel, the turbulence production in the boundary layer may be correspondingly controlled. As one example of a turbulent boundary layer turbulence control technique, it is known that 100 micron ribs spaced apart on 100 micron centers in a so-called riblet (see-saw) geometry acts within the turbulent boundary layer to controllably lessen the quantity of turbulence generated at the interface a few percent compared to an unribbed vessel. As another example, the turbulent boundary layer may be advantageously affected by ultrasonically adding energy to the medium locally along the interface in directions generally perpendicular to the flow direction. Ultrasonic turbulent boundary layer control techniques, however, pay the penalty of a comparatively-high power consumption, with all it's attendant disadvantages, and are accompanied by a comparatively-high level of emanated noise.